Recently, automobiles that run on electricity, such as an Electric Vehicle (EV), and a Plug-in Hybrid Electric Vehicle (PHEV) (hereinafter, referred to simply as “vehicles”) have gradually become popular. Such vehicles are equipped with a large-capacity storage battery, and store in the storage battery electric energy charged from the outside and run using the stored electric energy
As a method for supplying electric power to a vehicle storage battery from the outside, a method is available in which a charger installed in a vehicle receives the supply of alternating-current (AC) power from a 100V AC power source used in ordinary households and converts the AC power to direct-current (DC) power to charge a storage battery. This method requires a noise-eliminating device for eliminating noise, in order to prevent the inflow of noise into the AC power source. A charging apparatus having such a noise-eliminating device is disclosed, for example, in Patent Literature (hereinafter, referred to as “PTL”) 1.
PTL 1 discloses a charging apparatus including a switch in an intermediate grounding conductor that connects, to the ground, a ground side terminal of a Y capacitor that eliminates noise. The switch is configured to connect and disconnect the intermediate grounding conductor, and the charging apparatus disconnects the intermediate grounding conductor by controlling the switch when a security ground terminal is not connected to the ground. Thus, this switching prevents the occurrence of a large potential difference between a vehicle body and the ground even when the intermediate ground conductor is not connected to the ground sufficiently.
Meanwhile, as a method for supplying electric power to a vehicle storage battery from the outside, another method is available in which a quick-charging system provided outside a vehicle directly supplies large DC power to a storage battery.